Process for the manufacture of 1-bromo-4-acylaminoanthraquinones

ABSTRACT

A PROCESS FOR THE MANUFACTURE OF 1-BROMO-4-ACYLAMINOANTHRAQUINONES WHEREIN A 1- ACYLAMINOANTHRAQUINONE IS BROMINATED INTHE PRESENCE OF WATER.

United States Patent Ofiscc 3,804,863 PROCESS FOR THE MANUFACTURE OF l-BROMO 4-ACYLAMINOANTHRAQUINONES Eduard Moergeli, Muttenz, and Rudolf Winkler, Reinach, Basel-Land, Switzerland, assignors to Ciba-Geigy AG, Basel, Switzerland I p v v No Drawing. Continuation of abandoned application Ser. No. 727,052, May 6, 1968. This application June 7, 1971, Ser. No. 150,943 Claims priority, application Switzerland, May 9, 1967,

6,553/67; July 7, 1967, 9,704/67, v I Int. Cl. 1/36, 1/42 US. Cl. 260-377 "9 Claims ABSTRACT OF THE DISCLOSURE A process for the manufacture of l-bromo 4 acylaminoanthraquinones wherein a-l acylaminoanthraquinone is brominated inthe presence of water.

ing to the process described in Example 6 of theabove mentioned patent specification takes place even less satisfactorily than the chlorination" The extraordinary low speed of reaction of the bromination is a great disadvantagein an industrial process; Even under favorable conditions a yield of barely 50% is obtained and despit'alarge excess of bromine the resulting product is still contaminated with relatively large quantities of starting materiaL. I

The patent specification quoted also mentions'that on.v

halogenation of 1-acetylaminoanthraquinone dihalo'gen de:

rivatives are almost exclusively obtained. v

This invention is based on the surprising observation that 1-bromo-4-acylaminoanthraquinones may be obtained in almost quantitative yield and outstanding purity when the bromination of the l-acylaminoanthraquinone is car; ried out in the presence of water. v

Suitable starting substances are for example l-acylaminoanthraquinones, especially, 1 benzoylaminothraquinone, which may for example be substituted byhalogen atoms, or alkyl, alkoxy or nitro groups in' the benz'oyl" residue or in the benzene residue of *the' anthraquinone nucleus which is free from benzoylamino"groups,' and also- 1-alkanoylaminoanthraquinones which may forexample be substituted by halogen atoms 'or alkoxy, phenoxy, or

phenyl residues in the alkyl residue,"as well'as l-acyl; aminoanthraquinones in which the acyl residues are de'. rived from carbonic acid half-esters, heterocyclic carboxylic acids or organic sulphonic acids, especially arylsulphon ic acids. The following may be mentioned as examples:

1-acetylaminoanthraquinone, 1-chloroacetylaminoanthraquinone, 1-ethoxycarbonylaminoanthraquinone, 1,5-diacetylaminoanthraquinone, 1,S-dichloroacetylaminoanthraquinone, t 1,S-diethoxycarbonylaminoanthraquinone, l-benzoylaminoanthraquinone, 1-o-chlorobenzoylaminoanthraquinone,

quantity of water is needed when using an oxidizing agent I .70 v stlrred for a further 10 hours at the same temperature 3,804,863 Patented Apr. 16, 1974 1-p-chlorobenzoylaminoanthraquinone, 1-o-fluorobenzoylaminoanthraqninone, l-p-methylbenzoylaminoantbraquinone, 1-p-methoxybenzoylaminoanthraquinone, 1-m-nitrobenzoylaminoanthraquinone, 1-p-toluenesulphonylaminoanthraquinone, l-chloro-5-benzoylaminoanthraquinonc, 1-chloro-5-o-fiuorobenzoylaminoanthraquinone, 1'chloro-8 benzoylaminoanthraquinone, 1-nitro-5-acetylaminoanthraquinone, and 2-chloro-5-benzoylaminoanthraquinone.

The amount of the water present in the reaction may vary within wide limits; thus for example the reaction can be carried out in a completely aqueous medium, the amount of the water being selected so that a dispersion which can still be stirred is obtained. Thus it is advantageous to use at least 1 part, preferably at least 1.5 parts, of water for each part of the acylaminoanthraquinone. Significantly larger quantities of water may also be used without disadvantage, but the economy of the process is then impaired by the requisite larger vessels. The reaction can also be carried out in the presence of an acid, for example sulphuric acid or acetic acid, the acid concentration being advantageously not more than 50%, and/or in the presence of an inert organic solvent, in which case the proportion of the organic solvent can be substantially larger than that of the water.

Suitable inert organic solvents are for example chlorinated hydrocarbons for example tetrachloroethane, chlorobenzene, o-dichlorobenzene or especially nitrobenzene. The use of organic solvents has the advantage that the brominated acylaminoanthraquinones can be obtained in a single process stage, starting from aminoanthraquinone. The aminoanthraquinone is advantageously first acylated in the organic solvent, water is then added to the reaction mixture without isolating the acylaminoanthraquinone which is then brominated.

It is advantageous to use a large excess of bromine, preferably at least above the theoretical amount. When however the bromination is carried out in the presence of an oxidizing agent, for example an alkali metal chlorate, alkali metal persulphate or especialy an alkali metal bromate, an excess of bromine is unnecessary and it even suffices to use significantly less bromine than 1 mole of I Br for each bromine atom to be introduced, since the hydrogen bromide produce in the reaction is immediate- 1y re-oxidized to bromine.

"Since the function of the water during the bromination is' to bind-the resulting hydrogen bromide, only a small and "an organic solvent, advantageously not less than 3 mols of water for each mol of Br The most advantageous reaction temperatures are be tween 15 and C. Within these limits the bromination takes place remarkably rapidly and without side-reactions.

The brominated 1-acylaminoanthraquinones are as a rule produced in a homogeneous crystalline form and can easily be isolated from the reaction mixture by filtration. They are distinguished by high purity and can therefore be used without purification for subsequent reactions.

'In the examples which follow the parts, unlessotherwisc stated, denote parts by weight and the percentages denote percentages by weight.

EXAMPLE 1 '48 parts of bromine are added dropwise in 30 minutes to a mixture of 7.55 parts of sodium bromate, 32.7 parts of 1-benzoylaminoanthraquinone and 65.4 parts of water atv40 to 45. C. while stirring. The reaction mixture is and is then poured into about 1 liter of water in which 40 parts of sodium bisulphite have been dissolved, in

order to remove the excess bromine. Afterthoroughstin;v

ring the brominated product is filtered, washed until neutral and dried; 39.9 parts, corresponding to 98.3% of theory, of practically pure 1-bromo-4-benzoylaminoanthraquinone are obtained as a yellow crystalline powder of melting point 223 to 226 C., corrected. Found, Br 19.90%; calculated, Br 19.67%.

The 1-benzoylaminoanthraquinone used in the example was manufactured by benzoylation of l-aminoanthraquinone with benzoyl chloride in o-dichlorobenzene.

When the bromination is carried out in nitrobenzene in accordance with Example 6 of German patent specification No. 518,406 at 40 to 45 C. and using 4.8 times the theoretically required amount of bromine, a 1-bromo-4- benzoylaminoanthraquinone is obtained in 49% yield after 46 hours bromination which melts between 217 and 223 C. The product is still heavily contaminated with starting material and the bromine content is only 16.94%. More highly brominated compounds can be detected in the mother liquor.

EXAMPLE 2 48 parts of bromine are added dropwise at room temperature in about 30 minutes to a mixture of 7.55 parts of sodium bromate, 65.4 parts of water and 32.7 parts of l-benzoylaminoanthraquinone. The temperature is raised.

to 50-55 C. and the mixture stirred for 6 hours. Working-up takes place as in Example 1; 40.1 parts, corresponding to 98.8% of theory, of 1-brom0-4-benzoylaminoanthraquinone melting at 225 to 227 C. corrected, and having a bromine content of 19.45% are obtained. Only small quantities of starting material can be chromatographically detected in the product as impurities.

EXAMPLE 3 48 parts of bromine are added dropwise in 30' minutes" EXAMPLE 4 40 parts of bromine are added dropwise to amixture of 13.5 parts of potassium persulphate, 65.4 parts of water and 32.7 parts of 1-benzoylaminoanthraquinone in 30 minutes while stirring. The temperature is raised and the mixture is stirred for 6 hours at 50 to 55 C. Afterwork: ing-up 40.1 parts of 1-bromo-4-benzoylaminoanthraquinone corresponding to 98.8% of theory are obtained; m9el6ti3n; point 225 to 227 C., corrected, brominecontent 1 0.

EXAMPLE 64 parts of bromine are slowly added dropwise to..a

mixture of 32.7 parts of 1-benzoylaminoanthraquinone and 65.4 parts of water while stirring. The reaction mix:v

ture is stirred for 20 hours at 50 to 55 C. and isthen poured into a solution of 1,100 parts of water and .40 parts of sodium bisulphite. After thorough stirringuntil the excess bromine has disappeared the mixture is workedup; 39.6 parts of 1-bromo-4-benzoylamino-anthraquinone are obtained corresponding to 97.5% of theory. Melting point 225 to 228 C. corrected. Bromine content 19.64%.

The treatment with sodium bisulphite can be dispensed with if the excess bromine is recovered after thebromination by distilling it 011 at about 85 C., the same end re-" sult being achieved.

. 4 EXAMPLE 6 32.7 parts of 1-benzoylaminoanthraquinone are dissolved in 98 parts of concentrated sulphuric acid and then precipitated from the solution by dropwise addition of 200 parts of water at 45 C. while stirring and cooling; 48 parts of bromine are added dropwise to the suspension in 2 hours and the mixture is then stirred for 6 hours at 40 to 45 C. and 6 hours at 60 to 65 C.

After working-up with sodium bisulphite 38.5 parts of 1-bromo-4-beuzoylaminoanthraquinone melting at 224 to 228 C..corrected, and having a bromine content of 19.5% are obtained.

I 1 'EXAMPLE 7 A solution of 7.55 parts of sodium bromate in 32.7 parts of water is added dropwise in 3 hours to a mixture of 32.7 parts of 1-benzoylaminoanthraquinone, 65.4 parts of water and 32 parts of bromine at 50 to 55 C. The mixture is stirred for 3 hours at the same temperature and the brominated product is worked-up. The 1-bromo-4- benzoylaminoanthraquinone is obtained in a yield of 97.4% "of theory. Melting point 224 to 228 C. corrected. Bromine content 19.70%.

No higher brominated compounds can be chromatographically separated from the brominated product.

When the bromination is carried out with only 28 parts of bromine a brominated product having a bromine content of 14.07% and a melting point of 213 to 217 C. corrected is produced in 92.2% yield.

EXAMPLE 8 48 parts of bromine are added dropwise in 30 minutes to a mixture of 32.7 parts of 1-benzoylaminoanthraquinone, 98.1 parts of water and 7.55 parts of sodium bromate. The reaction mixture is stirred for 3 hours at to C. and worked-up as usual.

Yield 39.6 parts=97.6 of theory of 1-bromo-4- benzoylaminoanthraquinone. Melting point 225 to 228 C. corrected. Bromine content 19.7%.

EXAMPLE 9 64ip'arts of bromine are added dropwise in 30 minutes to' a mixture, of 32.7 parts of 1-benzoylaminoanthraquinone, 65.4 parts of water and 7.55 parts of sodium bromate Whilst stirring and the mixture is stirred for a further'Zi/g' hours without applying heat. 39.6 parts, corresponding to 97.5% of theory, of 1-bromo-4-benzoylaminoanthraquinone are obtained. Melting point 224 to 227 C., corrected. Bromine content 19.52%.

I EXAMPLE 10 48' parts of bromine are slowly added dropwise to a mixture of 26.5 parts of l-acetylaminoanthraquinone, 100

'parts of water and 7.55 parts of sodium bromate whilst stirring and allowing the temperature to rise to 30 C. The mixture is stirred for a further 21 hours at 20 to 25 C; and is then worked-up as stated in Example 1; 33.3 parts, corresponding,to.96.8% of theory, of practically 'pure' 1-acetylamino-4-bromanthraquinone are obtained.

36 parts of bromine are slowly added dropwise to a mixt-ure of 28.45 parts of 1-chloro-5-(o-fiuorobenzoylamino)-anthraquinone, parts of water and 5.67 parts of sodium bromate whilst stirring. The reaction mixture is stirred for a further 6 hours at 50 to 55 C. and then worked-up; 35.5 parts, corresponding to a yield of 97.5 of theory, of 1 chloro 8 bromo-S-(o-fluorobenzoylamino)-anthraquinone are obtained. Melting point 255 to 257 C. corrected. Bromine: found, 16.7%; chlorine: found, 7.68%.

When the 1 chloro 5 (o-fluorobenzoylamino)- anthraquinone is replaced by an equimolecular amount of l-(o-fluorobenzoylamino)anthraquinone (melting point 272 C., corrected), 31.4 parts of 4-bromo-1-(o-fiuorobenzoylamino)-anthraquinone melting at 198 to 199 C. corrected, are obtained. Bromine: found, 19.09%; calculated, 18.84%.

EXAMPLE 12 44.8 parts of bromine are added dropwise in 30 minutes to a mixture of 25.9 parts of 1-(p-toluenesu1phamino)- anthraquinone (melting point 227 C., corrected) and 65 parts of water whilst stirring. The mixture is stirred for a further 19 hours at room temperature and the reaction product worked-up as usual; 31 parts, corresponding to 97.2% of theory, of practically pure l-(p-toluenesulphamino)-4-bromanthraquinone melting at 165 to 168 C. corrected are obtained. Bromine: found, 17.48%; bromine: calculated, 17.51%. I

The recrystallized 1 (p-toluenesulp-hamino)-4-brornanthraquinone canbe quantitatively hydrolyzed to lamino-4-bromanthraquinone of melting point 179 to 180 C. corrected by means of concentrated sulphuric acid at room temperature.

EXAMPLE 13 A mixture of 153 parts of l-aminoanthraquinone, 540 parts of nitrobenzene and 103 parts of benzoyl chloride is stirred for 2 hours at 150 to 155 C. and for 1 hour at 185 to 190 C. The reaction mixture is cooled to room temperature, 5 parts of iodine, 266 parts of bromine and 200 parts of water are added, and the batch stirred for 2 hours at 50 to 55 C. 350 parts of sodium hypochlorite solution (active chlorine content 14%) are then added dropwise and the mixture is stirred for a further 18 hours at 50 to 55 C. The reaction product is filtered at 15 C., washed with methyl alcohol to remove nitrobenzene, and dried.

221.7 parts, corresponding to 82% of theory, of pure 1-benzoylamino-4-bromoanthraquinone of melting point 230 to 231 C. corrected are obtained. Bromine: calculated, 19.67%; bromine, found 19.47%.

The product can beconverted to 1-amino-4-hydroxyanthraquinone by heating in 5 %oleum.

EXAMPLE 14 13.3 parts of bromine followed by a solution of 1.68 parts of sodium bromate in 20 parts of water are added dropwise whilst stirring to a mixture of 21.7 parts of 1- benzoylaminoanthraquinone, 54 parts of nitrobenzene and 0.5 part of iodine. The mixture is thoroughly stirred for 16 hours at 60 to 65 C., cooled to 15 C., and the reaction product is filtered. After washing with alcohol and drying, 25.3 parts of 1-benzoylamino-4-bromoanthraquinone of melting point 230 to 231 C. corrected are obtained, corresponding to 93.3% of theory. The bromine content is 19.01%.

The same results are obtained when the theoretical amount of bromine (10.7 parts) is used.

EXAMPLE 15 A mixture of 17.2 parts of l-aminoanthraquinone, 90 parts of nitrobenzene and 14.5 parts of p-chlorobenzoyl chloride is stirred for 2 hours at 150 to 155 C. and 1 hour at 180 to 190 C. The reaction mixture is cooled to room temperature, 0.5 part of iodine, 30 parts of bromine and 20 parts of water are added, and the batch stirred for 2 hours at 50 to 55 C. 40 parts of sodium hypochlorite solution, corresponding to an active chlorine contentof 14%, are then added and the mixture stirred for a further 15 hours at 55 C. After working-up as described in Example 13, 28.7 parts of l-(p-chlorobenzoylamino)-4-bromoanthraquinone of melting point 238 to 239 C. corrected are obtained corresponding to 86.7% of theory.

6 EXAMPLE 16 When in Example 10 the 1-acetylaminoanthraquinone is replaced by an equimolecular amount of l-chloroacetylamino-anthraquinone (melting point 221 C., corrected) and the bromination is carried out in 65 parts of water in 24 hours at 50 to 55 C., 37.4 parts of l-chloroacetylarnino-4-bromanthraquinone are obtained corresponding to a yield of 98.9% of theory. Melting point 219 to 220 C. corrected. Found: bromine, 21.13%; chlorine, 9.40%. Calculated: bromine, 21.11%; chlorine, 9.63%.

EXAMPLE 17 24 parts of bromine are added dropwise in 30 minutes to a mixture of 15.5 parts of 1-acetylamino-5-nitroanthra quinone (melting point 277 C., corrected), 60 parts of Water and 3.75 parts of sodium bromate whilst stirring. The mixture is stirred for 20 hours at 50 to 55 C. and after working-up with sodium bisulphite solution, 18.4 parts of 1-acetylamino-4-bromo-5-nitroanthraquinone are obtained corresponding to a yield of 94.7% of theory. Melting point 262 to 263 C., corrected. Bromine: found, 20.31%; bromine: calculated, 20.53%.

EXAMPLE 18 28.8 parts of bromine are gradually added whilst stirring to a mixture of 21.7 parts of l-benzoylamino-S-chloroanthraquinone, 65 parts of water and 4.5 parts of sodium bromate, and the mixture then stirred for 23 hours at 50 to 55 C. After treatment with sodium bisulphite solu tion 26.1 parts, of 1-benzoylamino-4-bromo-5-chloroanthraquinone are obtained corresponding to 98.5% of theory. Melting point 216 to 219 C., corrected. Found: bromine, 18.29%; chlorine, 8.06%. Calculated: bromine, 18.13%; chlorine, 8.04%.

When the 1 benzoylamino 5 chloroanthraquinone is replaced by an equimolecular quantity of l-benzoylamino- 6-chloroanthraquinone and bromination carried out in 106 parts of water, 1-benzoylamino-4-bromo-6-chloroanthraquinone of melting point 218 to 220 C. corrected, is obtained in a yield of 98% of theory.

When in paragraph 1 the 1-benzoylamino-5-chloroanthraquinone is replaced by 1 benzoylamino 8 chloroanthraquinone 1 benzoylamino 4 bromo-8-chloroanthraquinone of melting point 217 C. corrected is again obtained in excellent quality and yield.

EXAMPLE 19 24 parts of bromine are gradually added dropwise to a mixture of 17 parts of 1 p methyl-benzoylaminoanthraquinone, 60 parts of water and 3.75 parts of sodium bromate whilst stirring. The reaction mixture is stirred for 20 hours at 50 to 55 C., worked-up as usual and 22.3 parts of l p methyl benzoylamino 4 bromoanthraquinone brominated in the tolyl residue are obtained; melting point 226 to 227 C. corrected. Bromine, found 31.8%; calculated 32.01%.

The bromination of l-(p-anisoylamino)-anthraquinone proceeds in a similar manner.

EXAMPLE 20 38.4 parts of bromine are added dropwise in 30 minutes to a mixture of 23.6 parts of 1-ethoxycarbonylaminoanthraquinone, 65 parts of water and 6 parts of sodium bromate whilst stirring. The reaction mixture is stirred for 21 hours at 50 to 55 C., then poured into a hot solution of 1,000 parts of water and 40 parts of sodium bisulphite, stirred, and the product filtered. The lumpy substance is finely ground and again treated with sodium bisulphite solution in the same Way. After filtering, washing and drying 28.6 parts of practically pure l-ethoxycarbonylamino 4 bromoanthraquinone of melting point 233 to 234 C. corrected are obtained, corresponding to 95.6% of theory. Bromine calculated, 21.35%; found, 21.45%.

The 1 ethoxycarbonylamino 4 bromanthraquinone can be saponified by heating for 4 hours at 70 at C.

in 95% sulphuric acid to give 1-amino-4-bromoanthraquinone of melting point 180 to 181 C. corrected.

EXAMPLE 21 96 parts of bromine are slowly added dropwise to a mixture of 32.2 parts of 1,5-di-(acetylamino)-anthraquinone (melting point 319 C. corrected), 110 parts of water and 15.1 parts of sodium bromate whilst stirring. The mixture is stirred for 22 hours at 50 to 55 C., worked-up as described in Example with solutions of 2,000 parts of water and 80 parts of sodium bisulphite at a time; 45.2 parts of 1,5-dibromo-4.8-di-(acetylamino)- anthraquinone melting at 330 C., with decomposition, are obtained. Bromine: found 33.41%; calculated, 33.29%.

EXAMPLE 22 32 parts of bromine are added dropwise in minutes to a mixture of 12.7 parts of 1,5-di-(ethoxycarbonylamino)-anthraquinone (melting point 309 C., corrected), 60 parts of water and 5 parts of sodium bromate whilst stirring. The reaction mixture is stirred for 21 hours at to C., poured into a solution of 1,000 parts of water and 40 parts of sodium bisulphite, and stirred for 1 hour at 90 C. After filtering, washing and drying, 17.1 parts of 1,5 di (ethoxycarbonylamino) 4,8 dibromoanthraquinone are obtained. Melting ponit 322 C., with decomposition, corrected. Bromine: found, 29.69%; calculated, 29.59%.

16 parts of bromine followed by a solution of 2.5 parts of sodium bromate in 20 parts of water are added dropwise to a mixture of 12.4 parts of l-(m-nitrobenzoylamino) anthraquinone (melting point 199 C. corrected), 48 parts of nitrobenzene and 0.5 part of iodine whilst stirring. After 20 hours intensive stirring at to C. the reaction product which has crystallized in yellow uniform small needles is filtered at 10 to 15 C., washed with alcohol and dried. 13.8 parts of l-(rn-nitrobenzoylamino) 4 bromoanthraquinone, melting point 280 to 281 C. corrected are obtained, corresponding to a yield of 91.8% of theory. Bromine: found, 17.04%; bromine: calculated, 17.71%.

What is claimed is:

1. A process for the manufacture of 1-bromo-4-acylaminoanthraquinones wherein a 1 acylaminoanthraquinone having a hydrogen atom in para-position to the acylamino group is brominated by the action of bromine in the presence of water at a temperature between 15 C. and C., the bromination mixture containing about 1.5 to 6 parts of water for each part of l-acylaminoanthraquinone present.

2. A process as claimed in claim 1 wherein a l-benzoylaminoanthraquinone is used as starting material.

3. A process as claimed in claim 1 wherein a l-alkanoylaminoanthraquinone is used as starting material.

4. A process as claimed in claim 1 wherein the bromination is effected in the presence of an oxidizing agent selected from alkali metal chlorate, alkali metal persulfate, alkali metal bromate, and sodium hypochlorite.

5. A process as claimed in claim 4 wherein an alkali metal bromate is used as oxidizing agent.

6. A process as claimed in claim 5 wherein 3 mols of bromine are used for each mol of the alkali metal bromate.

7. A process as claimed in claim 1 wherein the bromination is effected in the presence of 0.5 part by weight of sulfuric acid for each part by weight of water.

8. In a method for brominating l-acylaminoanthraquinones to obtain the 4-bromo-l-acylaminoanthraquinone, said bromination being effected by bromine in an inert organic solvent. the yield of said 4 bromo l-acylaminoanthraquinone being about 50%, the improvement therein which comprises brominating said l-acylaminoanthraquinones by the action of bromine in the presence of water at a temperature between 15 C. and 100 C., there being at least 3 moles of water for each mole of Br said improved process being characterized by a substantial increase in the conversion of the l-acylaminoanthraquinone to the 4-bromo-1-acylaminoanthraquinone.

9. A process as claimed in claim 8 wherein the bromination is effected in the presence of nitrobenzene as an inert solvent.

References Cited LVBS, Synthetic Dyes and Pigments, pp. 346 and 347 (1955).

LORRAINE A. WEINBERGER, Primary Examiner E. J. SKELLY, Assistant Examiner U.S. Cl. X.R. 260-371 

